1. Field of the Invention
The present invention relates to an apparatus and a method for mounting electronic components utilizing a plurality of mounting apparatus of electronic components, which have a plurality of component feeding units, and a component mounting unit for receiving electronic components from the feeding units and for mounting electronic components on a print circuit board.
2. Prior Art
Mounting apparatus of electronic components having an alternate capability are described in publications including Japanese patent laid-open publications No. Hei 5-167286 and No. Hei 8-172296. Such alternate capability is to alternate means for supplying electronic components and includes such alternate schemes as cassette-alternate, stage-alternate, and tray-alternate. These alternate schemes are, however, confined to a single mounting apparatus of electronic components.
Recently, there has been an increasing need for a production line for mounting electronic components where a plurality of mounting apparatus are simultaneously used, as the variety of the electronic components to be mounted has been increased.
In this type of multiple mounting-apparatus production line, there can be unpredicted imbalance of workload among the mounting apparatus due to the difference in their malfunction rates even when the original workload distribution is carefully designed among the mounting apparatus. This results in a lower throughput (number of print circuit boards through the mounting process per unit time) of the production line as a whole.
The present invention involves a production line for mounting electronic components having a plurality of mounting apparatus in which a mounting apparatus assumes a responsibility of another mounting apparatus for improving the overall production efficiency of the production line when the latter mounting apparatus has a longer cycle time than originally planned due to a higher malfunction rate of one of its component feeding units for supplying an electronic component, and when the former mounting apparatus can mount the same electronic component which is planned to be mounted by the latter mounting apparatus.
In the present invention, there is provided an apparatus as well as a method utilizing a plurality of mounting apparatus of electronic components, which have a plurality of component feeding units, and a component mounting unit for receiving electronic components from the feeding units and for mounting electronic components on a print circuit board. The apparatus has a memory means for recording a malfunction rate for each of its feeding units, and a computation means for comparing the malfunction rate to a predetermined value at a predetermined time for evaluating the malfunction rate. When the malfunction rate is higher than the value for a component feeding unit of a mounting apparatus, a selection means of the apparatus tries to choose an alternate component feeding unit on a different mounting apparatus, which supplies the same electronic component as the unit having a higher malfunction rate than the predetermined value. When there is such an alternate component feeding unit available, a control means of the apparatus has the alternate component feeding unit supplying the electronic component for mounting on the print circuit board, and has the component feeding unit with the malfunction rate higher than the predetermined value discontinuing supplying the electronic component.
In one embodiment of the present invention, the memory means records the numbers both for total and unsuccessful pick-up procedures for each of the component feeding units of all the mounting apparatus in the production line, and the malfunction rate is calculated from the two numbers at a predetermined time for evaluating the malfunction rates.
The configuration described above is able to prevent, utilizing the alternation scheme, the production line for mounting electronic components from having a lower production efficiency than expected even when one of the mounting apparatus has a longer cycle time due to a higher malfunction rate of its component feeding unit.